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1500 questions
211
votes
6 answers
Can I borrow a lunar rover?
According to Wikipedia there are 3 LRVs sitting on the moon, in very well defined locations. Would China, or whomever gets to the moon with a person next, be able to get in and drive around in an LRV left by the US?
The U.S. Apollo Lunar…
James Jenkins
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167
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What computer and software is used by the Falcon 9?
I don't know if this would be public, but what CPU / Microcontrollers are used and what software do they run on the Falcon 9? Do they use an OS or is it just bare metal programming?
I found some model rocket flight computers that are available for…
neelsg
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162
votes
3 answers
How did the Apollo computers evaluate transcendental functions like sine, arctangent, log?
Navigation with a sextant or maneuvers using gimbal angles might be two examples of cases where an Apollo computer might need to do trigonometry.
Trigonometric functions like sine, arctangent, etc. are transcendental, as are logarithms. You can't…
uhoh
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146
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12 answers
Couldn't I escape Earth's gravity traveling only 1 mph (0.45 m/s)?
It is said that in order for an object or a projectile to leave Earth's gravitational pull, it must reach Earth's escape velocity, meaning reach a speed of 7 miles per second (~11 km per second). Well, as far as I understand, you could easily escape…
user3339411
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145
votes
5 answers
Nudism in space: Why wear clothes anyway?
Currently, doing laundry in microgravity is an unsolved engineering problem. The result is that clean clothes on the International Space Station have become a consumable resource. Clean clothes get launched to the space station regularly. When they…
Philipp
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130
votes
4 answers
Do the planets really orbit the Sun?
We often say that the planets orbit the Sun, which is usually a reasonable approximation. But in reality both Sun and the planets orbit the center-of-mass/center-of-gravity of the whole solar system, not the center of the sun.
The Sun is by far the…
CodesInChaos
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122
votes
1 answer
How many extraterrestrial bodies have hosted a "lander" which returned images?
For the purposes of this question, we will consider a "lander" any probe which was sent to the surface of an extraterrestrial body or entered the atmosphere to a point which exceeds an air pressure of 5 x 10-7 kPa.
This question simply seeks the…
called2voyage
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118
votes
6 answers
What makes (or at least made) Ada the language of choice for the ISS's safety-critical systems?
We have it on good authority that Ada is widely used for "safety critical software" on at least the US side of the International Space Station.
Of all the possible languages to choose from, what are the aspects of Ada that make made it NASA's choice…
uhoh
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118
votes
6 answers
How much bigger could Earth be, before rockets wouldn't work?
hint: Apparently the Tsiolkovsky rocket equation does not actually say that you can launch a conventional rocket into orbit around an arbitrarily large and massive body.
I'm looking for a number based on scaling the earth radius and maintaining the…
uhoh
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115
votes
4 answers
What is the purpose of having a countdown during a rocket launch?
Every rocket launch has a countdown. But what purpose does it serve?
Hash
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113
votes
13 answers
What are the choices today for orbital mechanics simulation software?
I used to be familiar with the various choices out there for orbital mechanics simulation software. Alas, those days are gone. What are the choices today, preferably sorted by platform?
This question and others on this site might benefit from…
Erik
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111
votes
8 answers
If the astronauts on Apollo 11 had landed safely on the moon but could not take off, would there have been a rescue mission?
Say they landed on the moon but discovered the ship was damaged during the landing and they could not launch again.
What would have been the plan? Would another crew have been sent to rescue them? Would the astronauts just have to wait till they ran…
Diskdrive
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104
votes
3 answers
How did NASA achieve their live TV broadcast in 1969?
In 1969, NASA not only went to the moon, but broadcast the whole thing live on TV.
How did they achieve the TV broadcast? What technology did they need to use to send a video and audio signal from the moon to earth? Was there much of a lag?
JMK
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102
votes
3 answers
Is this "Attach Orbiter Here / Note: Black Side Down" sign on the Shuttle Carrier Aircraft real?
I found this image online, but is it a real message?
Baldrickk
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98
votes
3 answers
What happens to the Falcon 9 second stage after payload separation?
In a Falcon 9 launch, the second stage looks like it achieves orbit along with the payload. But is that impression accurate? Does SpaceX need to do anything to deorbit the stage?
I can see a few possibilities, but haven't been able to find which…
Hobbes
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